458 



Journal of Applied Microscopy. 



Fig. 2. — Epithelial Scale. 



microscope at the above magnification, the denticulated structure of the tooth-Uke 

 scales is clearly seen against the opaque background, if an ordinar)^ lamp with 

 seven-eighths inch flat wick is made use of for the illumination. The light should, 

 however, be indirect, and not pass through the image. Such a lamp is even 

 better than the electric incandescent lamp, and is much more convenient. 



This Cotswold-Merino fiber had been specially treated in 10 per cent, sodium 

 hvdroxide (NaOH) for one minute, washed in cold distilled water, carefully 

 dried between blotting papers, and finally in air at 100 degrees F., and then 

 mounted in 5 per cent, glycerine. It must be taken into consideration that 

 the foregoing process, a kind of destructive treatment, was intentionally adopted 



in order to bring out the scales more promi- 

 nently by partially dissolving the albuminous 

 structure of the fiber by the action of NaOH 

 solution. We notice on the lower extremity 

 of each scale, a very thin, membranous tissue, 

 attached to the inner wall of the scale, which 

 extends, also, directly to the cellular tube or 

 fiber proper. We have also observed that 

 these scales are sensitive to dry and moist 

 atmosphere. They expand and contract, and 

 this may be the reason why wool in fiber, or 

 in cloth garments, absorbs from 6 to 19 per 

 cent, of moisture, and no matter how dry such 

 wool may be, such absorption of water is persistently retained by the wool. But 

 it must not be understood that these scales are fastened in the manner here sug- 

 o-ested. It is, however, a theory resulting from many experiments and tests made 

 with a view to finding a solution for these armor-plate-like coverings in structures 

 which build up the so universally useful fiber of wool. The question arises, why 

 are these scales serrated ? To which we cannot find an answer. It is a fact that 

 all hair, and wool, of man and animals, is more or less serrated, but the wool, 

 and especially the finer classes, such as the Saxony and the Merinos, is the most 

 prominently serrated of all. Next we notice the inner cellular cavities here and 

 there filled with granules of pigment, and mineral salts, which give the various 

 colors to hair and wool, and hence we call these cavities pigment cells. If we take 

 an ordinary white wool, and boil a sample for the purpose of dissolving its tissues, 

 we will get a whitish, albuminous kind of fluid from which no traces of pigment can be 

 separated. But were we to treat a sample of mountain sheep wool, or of Scottish 

 black-face, we would find a decided black pigment corresponding, in fact, to the var- 

 ious colors of the hair, or wool in its natural state. We will here quote a typical 

 analysis of raw wool which shows that wool is by no means a simple substance. 

 This analysis is one of many we have made on raw wool, and represents a ver)^ 



fair average : Mineral matter, .... 5.8 



Suint and fatty matter, . . 45.2 



Pure fiber, 36.6 



Moisture, 12.4 



100.00 



